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Glossary of Terms

BABIP - Batting Average on balls put into play. A pitcher's average on batted balls ending a plate appearance, excluding home runs. Based on the research of Voros McCracken and others, BABIP is mostly a function of a pitcher's defense and luck, rather than persistent skill. Thus, pitchers with abnormally high or low BABIPs are good bets to see their performances regress to the mean. A typical BABIP is about .290.

EqA - Equivalent Average. A measure of total offensive value per out, with corrections for league offensive level, home park, and team pitching. EQA considers batting as well as baserunning, but not the value of a position player's defense. The EqA adjusted for all-time also has a correction for league difficulty. The scale is deliberately set to approximate that of batting average. League average EqA is always equal to .260. EqA is derived from Raw EqA, which is (H + TB + 1.5*(BB + HBP + SB) + SH + SF) divided by (AB + BB + HBP + SH + SF + CS + SB). REqA is then normalized to account for league difficulty and scale to create EqA.

VORP - Value Over Replacement Player. The number of runs contributed beyond what a replacement-level player at the same position would contribute if given the same percentage of team plate appearances. VORP scores do not consider the quality of a player's defense.

BB/9 - Walks allowed per every 9 innings.

K/9 - Strikeouts per every 9 innings.

K/BB - Strikeout to Walk ratio

WHIP - Walks plus hits allowed per inning pitched.

wOBA - The statistic wOBA (weight on base average) is now available in the player pages, leaderboards, team pages, my team pages, and the projections. wOBA, created by Tom Tango, is a version of linear weights that has been weighted to fit an OBP scale. The weights have been properly adjusted by season and for the minor leagues by season and by league.

Linear Weights - This is kind of long winded, but go here for an explanation.

BABIP - Batting Average on balls put into play. A pitcher's average on batted balls ending a plate appearance, excluding home runs. Based on the research of Voros McCracken and others, BABIP is mostly a function of a pitcher's defense and luck, rather than persistent skill. Thus, pitchers with abnormally high or low BABIPs are good bets to see their performances regress to the mean. A typical BABIP is about .290.

EqA - Equivalent Average. A measure of total offensive value per out, with corrections for league offensive level, home park, and team pitching. EQA considers batting as well as baserunning, but not the value of a position player's defense. The EqA adjusted for all-time also has a correction for league difficulty. The scale is deliberately set to approximate that of batting average. League average EqA is always equal to .260. EqA is derived from Raw EqA, which is (H + TB + 1.5*(BB + HBP + SB) + SH + SF) divided by (AB + BB + HBP + SH + SF + CS + SB). REqA is then normalized to account for league difficulty and scale to create EqA.

VORP - Value Over Replacement Player. The number of runs contributed beyond what a replacement-level player at the same position would contribute if given the same percentage of team plate appearances. VORP scores do not consider the quality of a player's defense.

BB/9 - Walks allowed per every 9 innings.

K/9 - Strikeouts per every 9 innings.

K/BB - Strikeout to Walk ratio

WHIP - Walks plus hits allowed per inning pitched.

wOBA - The statistic wOBA (weight on base average) is now available in the player pages, leaderboards, team pages, my team pages, and the projections. wOBA, created by Tom Tango, is a version of linear weights that has been weighted to fit an OBP scale. The weights have been properly adjusted by season and for the minor leagues by season and by league.

Linear Weights - This is kind of long winded, but go here for an explanation.

ERA+, no. Calculation of it could be improved on and there's no real need to pay attention to ERA, at least on a single-season basis. Over the course of a pitcher's career, sure. OPS+ is (and I'm sure I might get some flack for this) basically useless. You can't add OBP and SLG together because they're not on the same scale. It undervalues OBP by quite a bit.

Plus/Minus is pretty good. UZR is better, but neither should be taken seriously on a single-season basis (too much noise in the data). UZR/150 is being cited a lot but I don't really see why. There's really no point in prorating defensive numbers in my opinion.

My blog- analysis of the San Francisco Giants, Baseball, and Sabermetrics.

ERA+, no. Calculation of it could be improved on and there's no real need to pay attention to ERA, at least on a single-season basis. Over the course of a pitcher's career, sure. OPS+ is (and I'm sure I might get some flack for this) basically useless. You can't add OBP and SLG together because they're not on the same scale. It undervalues OBP by quite a bit.

Plus/Minus is pretty good. UZR is better, but neither should be taken seriously on a single-season basis (too much noise in the data). UZR/150 is being cited a lot but I don't really see why. There's really no point in prorating defensive numbers in my opinion.

I disagree with that first part, I'm a firm believer that a pitchers first job is to not allow any runs to score, regardless of how it's done. I know that the "+" stats need a 3 year basis of a stadium so YS and Citi Field are still working out little kinks... still I think that it is a fair measure since it adjusts to league averages.

I'll have to look up +/- again but there was a reason why I saw it as a better measure. I do see reason to measure defense numerically but I think it will be done better in the coming years. Did you hear about those cameras they installed in the top of every stadium which tracks like everyone on the defender, not sure if they went up yet but I read about it and it sounded interesting.

I disagree with that first part, I'm a firm believer that a pitchers first job is to not allow any runs to score, regardless of how it's done. I know that the "+" stats need a 3 year basis of a stadium so YS and Citi Field are still working out little kinks... still I think that it is a fair measure since it adjusts to league averages.

I'll have to look up +/- again but there was a reason why I saw it as a better measure. I do see reason to measure defense numerically but I think it will be done better in the coming years. Did you hear about those cameras they installed in the top of every stadium which tracks like everyone on the defender, not sure if they went up yet but I read about it and it sounded interesting.

Well, there are certain things a pitcher has no control over, and I don't think they should be held responsible for good or bad defense behind them. There's too much fluctuation year to year when it comes to defensive support, so I don't trust ERA on a single-season basis. ERA+ is pretty good for multiyear sampling though. OPS+ is just plain misleading. As much as I love B-Ref, I wish Sean would fix a few things.

And yes, I've heard of this new system- it'll fix a lot of the issues with Plus/Minus and UZR. I actually posted a thread on it a few months ago.

My blog- analysis of the San Francisco Giants, Baseball, and Sabermetrics.

WAR: Wins Above Replacement
A single statistic summarizing a player's offensive and defensive contributions. WAR calculates the amount of wins a player adds to his team compared to the contribution that would be expected from a replacement-level player. A replacement-level player is a player who can be signed for mimimum cost, i.e. someone on the waiver wire or a Minor League free agent. 0.0 WAR over a season denotes a replacement-level player, 2.0 is a regular starter, 5.0 is All-Star worthy and a WAR of 8 or above means the player is worthy of MVP consideration..
Is this 100% percent correct about players on waivers and WAR? Am I right or wrong that any player can be placed on waivers who is under contract? Plus, for the most part dont MLB teams keep it somewhat of a secret who is on waivers until they are claimed by another team? What I am getting at is how can someone have a higher WAR than a player that may or may not be on waivers, or what if there arent any players on waivers at the time? Also, what if there no free agent minor league players that are worth signing at the same time there are no players on waivers? Or, what if there is a player on waivers that had a higher WAR than 75% of players starting at the same position not on waivers? Does WAR include the post July "waiver required" trading period when teams usually rescind the waiver to avoid losing the player unless a trade can be made? So it seems to me that the player with the highest WAR in MLB can be put on waivers (highly unlikely), and when he is put on waivers does he no longer have a WAR, then when he is claimed by whoever he has to start his year over or he gets to keep the WAR he had prior to being put on waivers? Im just confused as to how a player can have a WAR higher than a player that no one knows who is! I am honestly confused about this stat!

Thumbs up for taking it way too literally and not understanding the stat. It is based on an average. Your average AAAA type player, or someone who would probably be readily available.

They arent picking some random guy on the waiver wire and saying "Mike Trout is this much better than him."

Oh ok so before Mike Trout was one before he was called up last year, then ended up with the highest WAR of all, Right or not? And what do you mean by taking it literally, how are you supposed to take it, sarcastically? If you dont take it literally, or by definition of the stat, then basically its a guess and WAR is a cant be used as a legit stat. Not all replacement players are the same, so the stat is basically saying he is better than whatever player you so choose, or he is better than someone that hasnt even had a chance to play in the Majors to prove his worth to a team, or he is better than an imaginary player. So if he was that much better than an imaginary player, that means he was compared to a player that does not exist. Now for instance lets use Mike Trout, say he gets injured and they call up a player and that player ends up with a 3.9 WAR while replacing Trout. Then Trout comes back does his WAR stay the same or do you have subtract 3.9 from his WAR because thats the WAR of his replacement. I was reading what all the stats mean on the one link in this forum and about half of them say predict, luck, or estimate. So if he need a replacement it wouldnt just be some player, it would be the best repplacement they could get....It is impossible to predict or estimate what a replacement player is gonna do if given a chance.....So how can WAR be taken literally if the definition of a replacement cant be taken literally!